Method for preparing cigarette filter

ABSTRACT

A method for preparing a cigarette filter of cellulose acetate fibers is provided, which is characterized by blooming a tow composed of cellulose acetate fibers, adding to the bloomed tow 1 to 20% by weight (based on the cellulose acetate fibers) of a plasticizer comprising as an ingredient a diglycerol ester compound and gathering the thus treated bloomed tow.

United States Patent 11 1 Sawada et a1.

METHOD FOR PREPARING CIGARETTE FILTER Inventors: Hideo Sawada; Jul iiKawamoto, both of Sakai, Japan Assignee: Daicel, Ltd., Osaka, JapanFiled: Aug. 22, 1973 Appl. No.: 389,083

US. Cl. 131/267; 156/180; 156/307 Int. Cl A2411 15/02 Field of Search156/180, 307; 131/267; 260/488 1 References Cited UNITED STATES PATENTS11/1961 Touey et al 131/208 June 24, 1975 3,017,309 1/1962 Crawford eta1 156/161 3,043,736 7/1962 Touey 1. 156/152 3,451,887 6/1969 Toucy eta1 161/168 Primary Examiner-Daniel J. Fritsch Attorney, Agent, orFirmWoodhams, Blanchard and Flynn [5 7] ABSTRACT 7 Claims, No Drawings 1METHOD FOR PREPARING CIGARETTE FILTER This invention relates to a methodfor preparing a cigarette filter. More particularly, the inventionrelates to a method for preparing a cigarette filter which comprisesadding a plasticizer containing as an ingredient a diglycerine estercompound to cellulose acetate fibers.

Tobacco smoke filters are very important in the cigarette manufacturingindustry, because they exhibit excellent effects in removing harmfulsubstances from tobacco smoke and, therefore, the demand for tobaccosmoke filters is increasing year by year. However, the requirements fora satisfactory cigarette filter tip are becoming more stringent andimprovements in the quality of cigarette filters are strongly desired.

In general, triacetin is used most widely in the industry as aplasticizer for cellulose acetate fibers constituting cigarette filters.However, triacetin has a relatively low boiling point (258C at 760 mmHg)and, though it is substantially not volatile at room temperature,triacetin may be released from filters when filter cigarettes are smokedand it will give a bitter taste in smoking. Thus, it is insufficientwith respect to the cigarette flavor and smoking taste.

Further, diacetate, dipropionate and dibutyrate esters of polyethyleneglycol are also used as plasticizers for cellulose acetate fibersconstituting cigarette filters. However, cigarette filters obtained byusing these plasticizers are defective in that the plasticizing effectsof such compounds are too strong, thereby causing unnecessarydissolution of cellulose acetate fibers and also they are stillunsufficient in cigarette flavor and smoking taste.

Dimethoxyethyl phthalate and triethyl citrate are also used asplasticizers, but, when they are used, it is necessary to heat filterrods at high temperatures exceeding room temperature for 2 to 4 hoursduring the step of curing the rods. Further, the obtained filters aregenerally not good with respect to the cigarette flavor and smokingtaste.

We have studied to obtain a cigarette filter for tobacco smoking whichdoes not cause any harm to the flavor and smoking taste and achieved themethod of the present invention.

That is, we have discovered that, when a plasticizer containing as aningredient a diglycerol ester compound is employed according to thisinvention a cigarette filter which does not harm the flavor and smokingtaste of cigarettes can be obtained and have now completed thisinvention based on this finding.

Diglycerol ester compounds to be used in this inven tion are preferablyacetate and propionate esters of diglycerol obtained by condensation anddehydration from two molecules of glycerol. These esters aretetraesters, triesters, diesters or mixtures thereof, which can berepresented by the following general formula:

wherein R stands for hydrogen or a lower alkyl group having one tofourcarbon atoms, preferably l to 2 carbon atoms, and whereas at least two Rshould be such lower alkyl groups.

These compounds can be used singly or in combination with anotherplasticizer. For example, they can be used together with triacetin,triethyleneglycol diacetate, etc. at an optional ratio.

In this invention, the plasticizer is added in an amount of l to 20% byweight (all percent values given hereinafter are on the weight basis),especially 5 to 10%, based on the cellulose acetate fibers.

In this invention, cellulose acetate fibers are used in the form of atow obtained by gathering 5,000 to 100,000 continuous fibers having asize of l to lo deniers. It is preferred that 10 to 30 uniform crimpsare given to the tow per 25 mm of the tow length.

Any method that can apply the plasticizer uniformly to cellulose acetatefibers may be adopted in this invention without any particularlimitation. For instance, the plasticizer is applied to both the upperand lower surfaces of the tow by a known method using a spray gun orwick. In case the amount of the plasticizer is too large locally,cellulose acetate fibers are so dissolved that dopes are formed.Accordingly, it is desired that the plasticizer is applied uniformly. incase the amount of the plasticizer is too small, a sufficient bonding isnot obtained among the fibers. In view of the foregoing, in thisinvention it is important that the plasticizer is distributed uniformlyin the interior of the tow band.

In this invention, the preparation of cigarette filters fromplasticizer-containing tows can be conducted by methods now industriallyconducted for the preparation of cigarette filters of cellulose acetatefibers.

The cigarette filter obtained by the above-mentioned method of thisinvention is characterized in that the inherent flavor and smoking tasteof tobacco are not damaged at all and there can be obtained cigarettefilters having satisfactory pressure drop hardness and other properties.Accordingly, this invention has a great industrial value.

The advantages of the method according to the present invention aresummarized as follows:

1. The above diglycerol ester compounds have high boiling points, andthey are odorless, colorless, tasteless and non-toxic. They have boilingpoints of to 230C at 3 mmHg which are higher than that of triacetin,and, therefore, there is no substantial possibility of their beinginhaled into the mouth and, even if they might be inhaled, the taste andflavor of the filter cigarette will not be damaged.

2. The diglycerol ester compounds themselves are stable andsubstantially not hydrolyzable and, accordingly, they do not give anyacidic smell.

3. They have sufficient plasticizing effects on cellulose acetate fibersat room temperature.

As mentioned above, the method by employing the above diglycerol estercompounds according to the present invention has many advantages in themanufacture of tobacco smoke filters and in the quality of the obtainedcigarette filter per se and it will be apparent that the method of thepresent invention is much more efiective in comparison with knownconventional methods.

The method of this invention will now be illustrated by reference toExamples. ln Examples, the rod hardness, pressure drop and nicotine andtar removal ratios were determined by the following methods,respectively. which have been conventionally employed in the art.

Hardness Pressure Drop It was expressed in terms of the resistancepressure in a water column height (mm) obtained when air was passedthrough a filter rod of a length of MD mm at a rate of 17.5 ml/sec.

Tar removal ratio and Nicotine removal ratio A sample filter tip wasattached to a cigarette and the obtained filter cigarette was smoked,when the amounts of nicotine and tar contained in the smoke passedthrough the filter and the amounts of nicotine and tar adsorbed on thefilter were respectively determined by ultraviolet spectroscope and gaschromatography. The respective ratios of nicotine and tar ad sorbed onthe filter based on their entire amounts were shown by as nicotine andtar removal ratios.

EXAMPLE 1 A cellulose acetate fiber tow of a filament denier of 4 and atotal denier of43,000 having 26 crimps per 25 mm of the tow length wasbloomed and diglycerol tetraacetate was added in the amount of 4.7% byweight to the bloomed cellulose acetate fiber tow by means of aplasticizer applicator. Then, the tow was fed to a filter rod makerapparatus and wrapped by means of a rice paper. Then, it was cut into alength of lOZ mm.

Such filter characteristics as the rod weight, the pressure drop, thehardness of the rod and the removal raties of nicotine and tar weredetermined with respect to the resulting rod. The results are shown inTable 1.

For the purpose of comparison, the above procedure was repeated in thesame manner by employing triacetin as the plasticizer in the amount of8% by weight, and the properties of the resulting filter rod weredetermined in the same manner. The results are shown in Table l asresults of Comparative Example l.

Each of the thus-obtained rods having a length of 102 mm was dividedinto 6 filter tips having a length of 17 mm. A tip of a commerciallyavailable Hi-Light cigerette (Trade name} was removed and the thusformed tip was attached instead. As a result of the smoking test, it wasfound that volatilization of the plasticizer is particularly small and agood taste and flavor was obtained in the case of the plasticizercomprising diglyc erol tetracetate without causing any harm to the tastein tobacco smoking.

EXAMPLE 2 Except that 6.5% by weight of a mixture of equal amounts oftriacetin and diglycerol tetracetate was used instead of diglyceroltetraacetate alone as the plasticizer, a filter rod was producedsubstantially by the same procedure as in Example 1. The properties ofthe resulting filter rod were as follows:

Pressure Drop Hardness Rod weigh! When this filter tip was attached tothe cigarette in the same manner as in Example 1, it gave a good tastein smoking.

EXAMPLE 3 Except that 7.0% by weight of a mixture of equal amounts oftriethyleneglycol diacetate and diglycerol tetraacetate was used insteadof diglycerol tetraacetate alone as the plasticizer, a filter rod wasproduced substantially by the same procedure as in Example 1.

Also, as Comparative Example 2, a filter rod was produced substantiallyby the same procedure as in Example 1, except that 6.9% by weight oftriethyleneglycol diacetatc alone was used instead of diglyceroltetraacetate alone.

The properties of the filter rods obtained above in Example 3 (7.0 wt.%of a mixture of equal amounts of triethyleneglycol diacetate anddiglycerol tetraacetate) and in Comparative Example 2 are shown in Table2.

Further, as a result of the smoking test, it was found that the filterrod produced by using a plasticizer comprising diglycerol tetraacetateas an ingredient was excellent particularly in the taste and flavor insmoking, compared to the filter rod produced by using triethyleneglycoldiacetate alone as the plasticizer.

What we claim is:

I. A tobacco smoke filter comprising a bundle of substantiallylongitudinally extending cellulose acetate fibers having a size of from1 to 16 denier per fiber, said fibers being substantially uniformlycoated with from I to 20% by weight, based on the weight of the fibers,of a plasticizer comprising as an ingredient a compound or a mixture ofcompounds having the formula:

cll ocore lYIlL OCUR wherein R is hydrogen or a lower alkyl group havingone to four carbon atoms and at least two R are said lower alkyl groups.

5 6 2. A tobacco smoke filter according to claim 1, in wherein R ishydrogen or a lower alkyl group having which the amount of plasticizeris from 5 to l()% by one to four carbon atoms and at least two R areweight, based on the weight of the cellulose acetate fisaid lower alkylgroups, and gathering the thustreated bloomed tow to form a filter.

A method for p pf Cigarette f f Cellu' 4. A method according to claim 3,wherein said plaslose acetate fibers whch Comprises l t s a f" ticizerconsists essentially of said ingredient. composed of cellulose acetatefibers, distributing uni- A method according to Claim 3 wherein Saidp|as forlnly throughout the bloomed tow from I to 20% y ticizer containsat least 50% by weight of said ingrediweight, based on the celluloseacetate fibers, ofa plasticizer comprising as an ingredient a compoundor a mix- 1() ture of compounds having the formula:

6. A method according to claim 5, wherein the remainder of saidplasticizer is a substance selected from the group consisting oftriacetin and the diacetate, dipropionate and dibutyrate esters ofpolyethylene glycol. aits-m li-lilil 7. A method according to claim 3,wherein the amount of said plasticizer is from S to 10%, based on thecellulose acetate fibers.

1. A TOBACCO SMOKE FILTER COMPRISING A BUNDLE OF SUBSTANTIALLYLONGITUDINALLY EXTENDING CELLULOSE ACETATE FIBERS HAVING A SIZE OF FROM1 TO 16 DENIER PER FIBER, SAID FIBERS BEING SUBSTANTIALLY UNIFORMLYCOATED WITH FROM 1 TO 20% BY WEIGHT, BASED ON THE WEIGHT OF THE FIBERS,OF A PLASTICIZER COMPRISING AS AN INGREDIENT A COMPOUND OR A MIXTURE OFCOMPOUNDS HAVING THE FORMULA:
 2. A tobacco smoke filter according toclaim 1, in which the amount of plasticizer is from 5 to 10% by weight,based on the weight of the cellulose acetate fibers.
 3. A method forpreparing a cigarette filter of cellulose acetate fibers, whichcomprises blooming a tow composed of cellulose acetate fibers,distributing uniformly throughout the bloomed tow from 1 to 20% byweight, based on the cellulose acetate fibers, of a plasticizercomprising as an ingredient a compound or a mixture of compounds havingthe formula:
 4. A method according to claim 3, wherein said plasticizerconsists essentially of said ingredient.
 5. A method according to claim3, wherein said plasticizer contains at least 50% by weight of saidingredient.
 6. A method according to claim 5, wherein the remainder ofsaid plasticizer is a substance selected from the group consisting oftriacetin and the diacetate, dipropionate and dibutyrate esters ofpolyethylene glycol.
 7. A method according to claim 3, wherein theamount of said plasticizer is from 5 to 10%, based on the celluloseacetate fibers.